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Dec. 13, 2011 -- Girls and young women who are vaccinated against human papillomavirus (HPV) appear to be no more likely than those who are not vaccinated to engage in sexually risky behaviors, a CDC survey finds.

HPV is the most common sexually transmitted infection in the U.S., with an estimated 6.2 million new infections each year.

With the approval of the first vaccine to prevent HPV infection in 2006 and the second in 2009, concerns emerged that vaccination might promote sexually risky behaviors.

Results from the CDC survey suggest these concerns may be unfounded, but researcher Nicole C. Liddon, PhD, warns against over-interpreting the findings.

Liddon is a research scientist with the CDC’s Division of Adolescent and School Health.

“This survey represents a snapshot in time, and we cannot rule out the possibility that the HPV vaccine leads to sexual risk taking,” she tells WebMD. “But this should help calm concerns of parents and (health care) providers to some degree.”

HPV Common in the Sexually Active

Among non-vaccinated girls and boys, infection with HPV is very common following initiation of sexual behavior.

By one estimate, 24% of teenaged girls in the U.S. between the ages of 14 and 19 and 45% of women in their early to mid-20s are infected with HPV.

For this reason, vaccination efforts target girls who are not yet sexually active. Current recommendations call for vaccination of girls and women ages 11-26 with the Cervarix or Gardasilvaccine. The Gardasil vaccine is also approved for use in boys.

In an effort to examine vaccine coverage rates and whether being vaccinated against HPV has any impact on behavior, Liddon and colleagues examined survey data from more than 1,200 young women between the ages of 15 and 24.

The women were participants in a CDC-sponsored survey examining sexual and reproductive health issues among teens and young adults.

The young women were surveyed between 2007 and 2008, after the first HPV vaccine became available.

Twice as many teens as women in their early 20s reported initiating the three-dose HPV vaccine series (30% vs. 15%). Liddon says this finding was not surprising because early efforts to promote the vaccine focused on teens.

The survey did not include information on the young women’s ages at HPV vaccination, and it was not clear if vaccination occurred before or after they became sexually active.

Among sexually active women, those who had initiated HPV vaccination were more likely than unvaccinated women to report that they consistently used a condom during sex.

The researchers conclude that this may be because young women who are more concerned about practicing safe sex are also more likely to be vaccinated against HPV.

HPV Vaccination Rates Lagging

In a report released last August, CDC officials reported that HPV vaccination rates among teens are lagging behind two other vaccines introduced for the age group at close to the same time.

Melinda Wharton, MD, MPH, of the CDC, says it appears many health care providers are not offering the HPV vaccine to their young female patients at age 11 or 12 as recommended, but are instead vaccinating girls later.

Wharton is deputy director of the National Center for Immunization and Respiratory Diseases.

“There is a sense that it is OK to wait until closer to the time that teens become sexually active,” she tells WebMD. “The problem is that you may be waiting until it is too late for vaccination to have an impact.”

She says pediatricians and other health care providers need to recommend the HPV vaccine as strongly as they recommend other immunizations.

The study is published in the latest issue of the American Journal of Preventive Medicine.